Overview of the 2014 Jupiter
aurora multi-instrument
campaign
- Key results
- Outstanding questions
- Lessons learned
S.V. Badman (1), R.L. Gray (1), B. Bonfond (2), M. Fujimoto (3), M. Kagitani (4), Y. Kasaba (4), S.
Kasahara (3), T. Kimura (3), H. Melin (5), G. Murakami (3), J.D. Nichols (5), T. Sakanoi (4), A.J. Steffl
(6), C. Tao (7), F. Tsuchiya (4), T. Uno (4), A. Yamazaki (3), M. Yoneda (4), I. Yoshikawa (8), K.
Yoshioka (8)
(1) Lancaster University, UK, (2) Université de Liège, Belgium, (3) JAXA Institute of Space and Astronautical Science,
Japan, (4) Tohoku University, Japan, (5) University of Leicester, UK, (6) Southwest Research Institute, USA, (7) NICT,
Japan, (8) University of Tokyo, Japan
The global picture
L03104
• Reconnection
outflows/plasmoids
and inflows/
dipolarisations
RADIOTI ET AL.: AURORAL SIGNATURES OF RECONNECTION
L03104
Radioti et al.
(2013)
Figure 1. Raw HST-ACS images showing the FUVauroral emission at the north pole of Jupiter, taken (top) on 15 May 2007
and (bottom) on 5 March 2007. The arrows indicate the main auroral features: the main oval, the Io footprint and its trail, the
polar emissions and the polar dawn spots.
(d spot). The location of the observed polar dawn spots is
close to the theoretical projected location of the Vasyliūnascycle tail X-line in the ionosphere as suggested by Cowley
et al. [2003].
[6] We analysed the data obtained between February 21
and June 11, 2007. Polar dawn spots are observed on 17 out
of 37 days. The spots last from 10 minutes to !1 hour.
Within this time period the emitted power of a typical spot,
such as spot ‘‘c’’ in Figure 2 can reach 1 GigaWatt above the
background emission. The maximum brightness is !250 kR
above the background emissions, which corresponds to an
input energy flux of 25 mWm"2. The spatial dimensions of
the spots, are typically !3000 # 1000 km and they are
located !1200 km poleward of the central position of the
main oval. The spots are corotating with the planet, since
their position in S3 longitude and latitude remains almost
especially for the radial distance rather than the longitude.
Given the inaccuracy of the VIP4 model we consider the
mapped position as an approximation. The histogram in
Figure 3 shows the local time interval to which the spots
map, during each day of observation. Since the polar dawn
spots are corotating with the planet, their position in local
time changes with time. The histogram shows the local time
interval the polar dawn spots cover during each day of
observation. The majority of the spots are observed between
04:00 and 09:00 LT.
[9] The bottom plot of Figure 3 shows an equatorial view
of the source region of the polar dawn spots presented by
the dashed area. The region is constrained by the 04:00 and
09:00 LT meridians, the range to which the majority of these
events maps. It can not be ascertained whether spots appear
before 04:00 LT (dashed line meridian) or not, because of
Kasahara et al. (2013)
The global picture
L03104
• Reconnection
outflows/plasmoids
and inflows/
dipolarisations
RADIOTI ET AL.: AURORAL SIGNATURES OF RECONNECTION
L03104
Radioti et al.
(2013)
• Injections (all LT)
Figure 1. Raw HST-ACS images showing the FUVauroral emission at the north pole of Jupiter, taken (top) on 15 May 2007
and (bottom) on 5 March 2007. The arrows indicate the main auroral features: the main oval, the Io footprint and its trail, the
polar emissions and the polar dawn spots.
(d spot). The location of the observed polar dawn spots is
close to the theoretical projected location of the Vasyliūnascycle tail X-line in the ionosphere as suggested by Cowley
et al. [2003].
[6] We analysed the data obtained between February 21
and June 11, 2007. Polar dawn spots are observed on 17 out
of 37 days. The spots last from 10 minutes to !1 hour.
Within this time period the emitted power of a typical spot,
such as spot ‘‘c’’ in Figure 2 can reach 1 GigaWatt above the
background emission. The maximum brightness is !250 kR
above the background emissions, which corresponds to an
input energy flux of 25 mWm"2. The spatial dimensions of
the spots, are typically !3000 # 1000 km and they are
located !1200 km poleward of the central position of the
main oval. The spots are corotating with the planet, since
their position in S3 longitude and latitude remains almost
Mauk et al.
(2002)
especially for the radial distance rather than the longitude.
Given the inaccuracy of the VIP4 model we consider the
mapped position as an approximation. The histogram in
Figure 3 shows the local time interval to which the spots
map, during each day of observation. Since the polar dawn
spots are corotating with the planet, their position in local
time changes with time. The histogram shows the local time
interval the polar dawn spots cover during each day of
observation. The majority of the spots are observed between
04:00 and 09:00 LT.
[9] The bottom plot of Figure 3 shows an equatorial view
of the source region of the polar dawn spots presented by
the dashed area. The region is constrained by the 04:00 and
09:00 LT meridians, the range to which the majority of these
events maps. It can not be ascertained whether spots appear
before 04:00 LT (dashed line meridian) or not, because of
Kasahara et al. (2013)
The global picture
L03104
• Reconnection
outflows/plasmoids
and inflows/
dipolarisations
RADIOTI ET AL.: AURORAL SIGNATURES OF RECONNECTION
L03104
Radioti et al.
(2013)
• Injections (all LT)
Figure 1. Raw HST-ACS images showing the FUVauroral emission at the north pole of Jupiter, taken (top) on 15 May 2007
and (bottom) on 5 March 2007. The arrows indicate the main auroral features: the main oval, the Io footprint and its trail, the
polar emissions and the polar dawn spots.
Mauk et al.
(2002)
especially for the radial distance rather than the longitude.
• Interchange
(d spot). The location of the observed polar dawn spots is
close to the theoretical projected location of the Vasyliūnascycle tail X-line in the ionosphere as suggested by Cowley
et al. [2003].
[6] We analysed the data obtained between February 21
and June 11, 2007. Polar dawn spots are observed on 17 out
of 37 days. The spots last from 10 minutes to !1 hour.
Within this time period the emitted power of a typical spot,
such as spot ‘‘c’’ in Figure 2 can reach 1 GigaWatt above the
background emission. The maximum brightness is !250 kR
above the background emissions, which corresponds to an
input energy flux of 25 mWm"2. The spatial dimensions of
the spots, are typically !3000 # 1000 km and they are
located !1200 km poleward of the central position of the
main oval. The spots are corotating with the planet, since
their position in S3 longitude and latitude remains almost
Given the inaccuracy of the VIP4 model we consider the
mapped position as an approximation. The histogram in
Figure 3 shows the local time interval to which the spots
map, during each day of observation. Since the polar dawn
spots are corotating with the planet, their position in local
time changes with time. The histogram shows the local time
interval the polar dawn spots cover during each day of
observation. The majority of the spots are observed between
04:00 and 09:00 LT.
[9] The bottom plot of Figure 3 shows an equatorial view
of the source region of the polar dawn spots presented by
the dashed area. The region is constrained by the 04:00 and
09:00 LT meridians, the range to which the majority of these
events maps. It can not be ascertained whether spots appear
before 04:00 LT (dashed line meridian) or not, because of
Kasahara et al. (2013)
The global picture
L03104
• Reconnection
outflows/plasmoids
and inflows/
dipolarisations
RADIOTI ET AL.: AURORAL SIGNATURES OF RECONNECTION
L03104
Radioti et al.
(2013)
• Injections (all LT)
Figure 1. Raw HST-ACS images showing the FUVauroral emission at the north pole of Jupiter, taken (top) on 15 May 2007
and (bottom) on 5 March 2007. The arrows indicate the main auroral features: the main oval, the Io footprint and its trail, the
polar emissions and the polar dawn spots.
Mauk et al.
(2002)
especially for the radial distance rather than the longitude.
• Interchange
(d spot). The location of the observed polar dawn spots is
close to the theoretical projected location of the Vasyliūnascycle tail X-line in the ionosphere as suggested by Cowley
et al. [2003].
[6] We analysed the data obtained between February 21
and June 11, 2007. Polar dawn spots are observed on 17 out
of 37 days. The spots last from 10 minutes to !1 hour.
Within this time period the emitted power of a typical spot,
such as spot ‘‘c’’ in Figure 2 can reach 1 GigaWatt above the
background emission. The maximum brightness is !250 kR
above the background emissions, which corresponds to an
input energy flux of 25 mWm"2. The spatial dimensions of
the spots, are typically !3000 # 1000 km and they are
located !1200 km poleward of the central position of the
main oval. The spots are corotating with the planet, since
their position in S3 longitude and latitude remains almost
Given the inaccuracy of the VIP4 model we consider the
mapped position as an approximation. The histogram in
Figure 3 shows the local time interval to which the spots
map, during each day of observation. Since the polar dawn
spots are corotating with the planet, their position in local
time changes with time. The histogram shows the local time
interval the polar dawn spots cover during each day of
observation. The majority of the spots are observed between
04:00 and 09:00 LT.
[9] The bottom plot of Figure 3 shows an equatorial view
of the source region of the polar dawn spots presented by
the dashed area. The region is constrained by the 04:00 and
09:00 LT meridians, the range to which the majority of these
events maps. It can not be ascertained whether spots appear
before 04:00 LT (dashed line meridian) or not, because of
• Main auroral oval
Transition region?
Kasahara et al. (2013)
Overview of 2014 campaign
(a) HST
(e) Solar wind
main oval polar
emission
spectroscopy
Previous
campaign[8]
spectroscopy
slit
Wavelength (um)
Aurora [15]
IR H3+ and H2 aurora
-atmospheric temperature
-ion density
energy transport
scenario 1
auroral
emission
imaging
FUV H2 aurora
-spatial position of energy release
-energy of precipitating auroral electrons
plasma torus
heating
energy
release
Peak
(c) Kitt
WIYN
Visible IPT
-imaging of visible ion IPT
-cold electron temperature of IPT
EUV IPT and aurora
-hot electron temperature of IPT
-precipitation of auroral electrons
WIYN/SparsePak
FOV
brightness
SIII 68nm
[cts/1000s]
spectroscopy
400"
(red:dusk, blue:dawn)
279
IPT [3]
imaging
IPT at 673.1 nm [11]
90-108nm
[cts/1000s]
Rayleighs/Angstrom
MHD solar wind model [5]
-dynamic pressure at Jupiter
JAXA
400"
Wavelength (Angstrom)
Sunspot number
[Hathaway, NASA, MSFC]
Solar wind
compression?
energy transport
scenario 2
HISAKI/
(b) EXCEED
Io
footprint
Aurora[9]
280
281
Day of year (2000)
282
IPT (top) and aurora (bottom) [4]
IPT [17]
Intensity (arbitary units)
Intensity (Wm-2um-1sr-1)
(d) GEMINI
spectroscopy
Wavelength (um)
Overview
X
(a) HST
(e) Solar wind
main oval polar
emission
spectroscopy
Wavelength (um)
Aurora [15]
IR H3+ and H2 aurora
-atmospheric temperature
-ion density
auroral
emission
imaging
FUV H2 aurora
-spatial position of energy release
-energy of precipitating auroral electrons
plasma torus
heating
energy
release
MHD solar wind model [5]
-dynamic pressure at Jupiter
JAXA
Peak
(c) Kitt
WIYN
(b) EXCEED
Visible IPT
-imaging of visible ion IPT
-cold electron temperature of IPT
EUV IPT and aurora
-hot electron temperature of IPT
-precipitation of auroral electrons
WIYN/SparsePak
FOV
(red:dusk, blue:dawn)
279
IPT [3]
imaging
IPT at 673.1 nm [11]
90-108nm
[cts/1000s]
spectroscopy
400"
brightness
SIII 68nm
[cts/1000s]
400"
Wavelength (Angstrom)
Sunspot number
[Hathaway, NASA, MSFC]
Solar wind
compression?
energy transport
scenario 2
Rayleighs/Angstrom
Io
footprint
Aurora[9]
280
281
Day of year (2000)
282
IPT (top) and aurora (bottom) [4]
IPT [17]
Intensity (arbitary units)
energy transport
scenario 1
Previous
campaign[8]
spectroscopy
slit
Intensity (Wm-2um-1sr-1)
(d) GEMINI
spectroscopy
Wavelength (um)
HST FUV aurora 1-16 Jan 2014
• 14 HST orbits over 16 days around Jupiter opposition
• Capture solar wind variability (in theory)
• STIS SrF2 time-tag imaging and spectroscopy
UV aurora 1-16 Jan
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
• Dimming of
main
emission,
particularly
on dawn side
• Bright low
latitude
features
• Polar flares
(m)
(n)
(o)
Power [GW]
Total auroral power
• HST observes power of
FUV aurora (main oval +
low latitude + polar)
• Hisaki EUV auroral
observations
– quasi-continuous
– no spatial resolution
• Decrease in emitted
power over the
campaign
• Three transient, highpower peaks seen by
Hisaki
Auroral power
• Define auroral regions
– Main oval
– Polar
– Low latitude
Regional auroral power
• High spatial resolution of
HST allows us to determine
power in each region
• Main oval power
decreases from ~480 GW
to 170 GW
• Low latitude power
roughly constant except
for large increases on
days 4 and 11
• Polar power shows short
timescale (minutes)
variability but no longterm decrease
Regional auroral power
• Transient peaks in power
are associated with lowlatitude emissions [Kimura
et al., 2015]
• Decrease in total auroral
power follows the main
oval
Equatorward shift of main oval
• Main oval shifts ~1° equatorward
• Comparable to previous
observations over longer
timescales [Grodent et al., 2008;
Bonfond et al., 2012]
HST spectroscopy
• Electron energy can be
estimated from UV
spectra because UV is
subject to absorption
• The colour ratio is defined
as: CR= Iunabsorbed / Iabsorbed
647
Tao et al., JGR, 2015
• The CR depends on
electron energy: more
energetic electrons travel
deeper and subsequent
emission undergoes more
absorption
• Higher CR = higher
energy auroral electrons
HST spectroscopy
• HST/STIS spectral
observations show that
the CR of the main oval
was approximately
constant over Jan 2014
• CR~2.5 corresponds to
auroral electron energy of
<W>~150 keV
Tao et al., JGR, submitted
Decrease in auroral power
• If the precipitating electron energy was constant, a
decrease in auroral power can be attributed to:
– Lower electron flux, i.e. lower electron density in
magnetosphere source region
– Higher electron temperature in magnetosphere source
region
Reduced electron density
• Magnetospheric expansion
leading to decrease in
electron density
• Solar wind dynamic pressure
propagated from 1 AU
(OMNI) measurements [Tao
et al., 2005; 2015]
• This is different from the
increase in auroral currents
predicted by conservation of
angular momentum during
an expansion [e.g.
Southwood and Kivelson,
2001; Cowley et al., 2007]
Increase in source electron
temperature
• Increase in hot plasma transport would increase Wth:
– Auroral signatures of hot plasma injections are observed
• This type of signature previously related to enhanced Io
volcanic activity and mass loading [Bonfond et al.,
2012]
Mass-loading from Io
• Observations of Io’s neutral
sodium nebula at
Haleakala do not indicate
an increase in neutral
density (Io source)
[Yoneda et al., 2010; 2015]
• Hisaki EUV observations of
the S and O emission lines
in the inner Io plasma torus
also suggest the torus
density was steady over
the interval [Tsuchiya et
al., 2015]
• No indication of increased
mass loading from Io
Yoneda et al., Icarus, 2015
Injections driven by reconnection
• Auroral observations on day 11 show
– super-rotating polar dawn spot
– bright low latitude emissions
– disturbed main emission
Injections driven by reconnection
• Auroral observations on day 11 show
– super-rotating polar dawn spot
• 7000 km/s electron jet measured during prolonged
reconnection interval by Kasahara et al. [2012]
– bright low latitude emissions
• hot plasma injections at 9-27 Rj [Mauk et al., 1999; 2002]
– disturbed main emission
• enhanced flow shear & transition between dipolarisation inflow
and injection
00_142
01_289
Burst 141.4
Burst/LF extension 288.8
18
12
141.4
Not visible, in torus
141.4
288.8
Correlation nKOM spot/injection until 142 (9 RJ ).
Several nKOM sources and injections until 290.
a
The different columns correspond to (1) time of observation of the HOM burst (and its possible low-frequency extension), (2) Galileo position, (3) time of det
tion of the first nKOM (the new source), (4) time of measurement of the first injection (in most case dispersionless injections) and, (5) possible correlation betwe
nKOM spots and dispersed injection seen during the subsequent Jovian rotation passes with event seen at r < 15 RJ are underlined.
Global reconfiguration
the Rice Convection Model concerning the plasma convection in the inner disk [see, for example, Pontius et
1986]. It may be possible that the inward injections of energetic particles result in outward motions of the ther
plasma, leading to the formation of “fingers of thermal plasma” as seen in the model. What we show,
nevertheless, is that this would imply a form of explosive and large-scale perturbations that is not describe
the current models. In Figure 8, we simply suggest that the sector of longitude where the injection occurs co
be a region of enhanced radial transport of the thermal plasma due to a form of interchange.
• Galileo studies show tail
reconnection signatures
closely associated with HOM
radio bursts and new nKOM
signatures at outer Io plasma
torus [Louarn et al., 2014]
• Non-Io DAM enhanced by
solar wind shocks (=
reconfigurations?) [Hess et
al., 2014]
• Identification of possible
HOM and non-Io DAM
enhancements in WIND
observations on 11 Jan
[Gray et al.,
in prep.]
LOUARN ET AL.
Louarn et al., JGR, 2014
Figure 8. Sketches of global magnetospheric disturbances, showing the location of the different dynamical processes
their relationships.
©2014. American Geophysical Union. All Rights Reserved.
4
What have we learned?
• 70% decrease in auroral power observed without a
change in Io volcanic activity or a solar wind shock
[Badman et al., GRL, 2016]
• Transient power enhancements are related to low
latitude emissions [Kimura et al., GRL, 2015]
• Signature of super-rotating reconnection inflow
detected [Gray et al., in prep]
• Possible formation of low latitude emissions following
reconnection inflows [Gray et al., in prep.; after Louarn
et al., 2014]
Questions to address
• How do polar spots evolve?
– Longer coverage, sequences of spots including super-rotating spots (HST, UVS,
JIRAM, Waves)
• How do low-latitude emissions evolve?
– Observe at all LT, measure particle energy and PAD (Imaging, Waves, particles)
• How does precipitating electron energy vary? (UV spectra, particles)
• How do we identify Io volcanic activity and over what timescale does
it influence the magnetosphere? (GBIR volcanoes, Na nebula, Hisaki
torus)
• What is the role of the solar wind?
– Need in situ measurements (MAG, particles), accurate propagation models,
good imaging cadence
• What is the global picture? (HST)
Interesting Saturn observations
nal of Geophysical Research: Space Physics
10.1002/2015JA021008
A01211
A01211
BADMAN ET AL.: SATURN AURORAL IO
BADMAN ET AL.: SATURN AURORAL ION AND ELECTRON BEAMS
A01211
Figure 1. (left and middle) Cassini’s trajectory and mapp
DOYs 318–324 (13–19 November 2008) in KSM coordin
Y is positive toward dusk, and the X-Z plane contains the
red lines indicate the extreme positions of the magneto
0.01 nPa and 0.1 nPa, obtained from the Arridge et al. [2
of Cassini’s trajectory with the sunward direction toward
red dots mark latitudes at intervals of 10° and the noon-mi
1 pixel = 0.5 ! 0.5 mrad and the FOV for these observations
was 42 ! 42 pixels. The total exposure time for each image
was "30 min. The images in Figure 2 have been projected
onto a 0.25° ! 0.25° planetocentric polar grid using an
estimated peak emission height of 1100 km above the 1 bar
reference spheroid (T. S. Stallard et al., Peak emission altitude of Saturn’s H+3 aurora, unpublished manuscript, 2011).
The orientation is such that the observer is looking down
onto the pole with the sunward direction (12:00 LT) at the
bottom, dawn (06:00 LT) to the left and dusk (18:00 LT) to
Figure 5. Energetic beams of ions and electrons in regions of field-aligned currents on 2008-320 12:00–
Figure 3. Overview of Cassini observations on 25 June 2009: (a and b) color-coded count rates (proportional to energy24:00
flux) UT. From top to bottom: fluxes of 200 keV to 1 MeV electrons from LEMMS, fluxes of 1 eV to
of ions and electrons, respectively, from CAPS/IMS/SNG and CAPS/ELS, averaged over all eight anodes; (c–e) r, θ, and28ϕ keV field-parallel (upward) electrons from ELS, RPWS electric field spectrogram, ion fluxes measured
+
+
components of the magnetic field measured by MAG; (f and g) flux of energetic H and O ions, respectively, from MIMI;
by INCA, field-aligned current regions determined from MAG data. The vertical dashed lines on first to
and (h) electric field power spectrum measured by RPWS. Time 1 marks Cassini’s exit from the open field lines of thefourth
lobe panels indicate the boundaries of the upward and downward current regions plotted in the fifth
into the region of closed field lines. Time 3 marks the abrupt transition from hot, tenuous plasma into cool, dense, inner
panel. The labeled arrow at the top indicates the start time of VIMS auroral image iii shown in Figure 2a.
Plasmapause
Thomsen et al. (2014)
Energetic downward current
Badman et al. (2012)
the r
each
23:0
[11]
sity,
nonc
emis
prod
for li
mult